An optical scanning device is provided in an image forming apparatus such as an electrophotographic color copier or an electrophotographic color printer. The optical scanning device irradiates a plurality of charged image bearing members with light to form electrostatic latent images on the respective image bearing members. A housing of the optical scanning device includes an accommodation portion having a face an opening and a cover portion covering the opening. An optical scanning system is provided inside the accommodation portion. The cover portion has exit openings for respective beams of light emitted from the optical scanning system. The exit openings each correspond to one of the image bearing members. Further, the exit openings are each covered by a light transmitting member. The light transmitting member is capable of transmitting light emitted from the optical scanning system.
The light transmitting members are provided to prevent toner, dust, or the like from entering the inside of the optical scanning device. Optical properties may be deteriorated by adhesion of toner, dust, or the like to some or all of optical components located inside the optical scanning device. Deterioration of the optical properties results in deterioration of quality of an image formed on a recording medium such as paper.
Alternatively, the optical properties may also be deteriorated by adhesion of toner, dust, or the like to outer surfaces of some or all of the light transmitting members. Therefore, it is necessary to clean outer surfaces of the respective light transmitting members periodically. For example, Patent Literature 1 discloses an automatic cleaning device that automatically cleans outer surfaces of respective light transmitting members. The automatic cleaning device moves a plurality of cleaning holders in the same direction simultaneously by respective screw shafts arranged to extend in longitudinal directions of the light transmitting members. The cleaning holders each hold a single cleaning member. When the cleaning holders move along respective movement tracks, the cleaning members each slide on the outer surface of a corresponding one of the light transmitting members. Through the above, the light transmitting members are cleaned simultaneously. Further, the above automatic cleaning device reverses a direction of movement of each cleaning holder by using reaction force of an operation return spring.